What about fuel types & gas mileage?

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Comments

  • shiposhipo Member Posts: 9,148
    On the whole, I agree with your post, however, for the sake of clarity, I'd like to offer a couple of corrections.

    Detonation: The spontaneous combustion of very small pockets of "End Gas" (or not so small in the case of heavy detonation). Said combustion is caused by the rapidly rising pressure and resultant temperature of the combustion process as the flame front moves across the combustion chamber. Very light detonation is actually considered harmless (by some engineers) and is possibly beneficial for both performance and fuel economy. Moderate detonation is of concern because if left unchecked, it will usually progress to heavy detonation. Heavy detonation WILL destroy an engine in a matter of minutes (at the very most).

    Pre-Ignition: The spontaneous combustion of a large portion of the intake charge BEFORE the spark event (hence the name "PRE-Ignition"). Pre-Ignition WILL destroy an engine in seconds.

    Best Regards,
    Shipo
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    Many people don't realize what "pinging" actually is. What you are hearing is your internal engine parts rattling around, and in some extreme cases, the cylinder walls of the engine block are actually flexing from the stress.

    Pre-ignition can easily bore a hole right through the top of a piston.
  • kvngwynthkvngwynth Member Posts: 2
    BRAVO. :D Well said. I am a girl, love cars and "tuning" up cars but keeping it in "almost" original condition. A car doesn't have to look all souped up to have the power it could and should have. I LOVE USING PREMIUM GAS FOR ALL MY CARS TOO. Have been driving for 20 years without one single ticket. Don't do drugs, don't smoke and don't drink alcohol, am too straightforward at some times but "refreshingly honest and naieve" according to my husband whom I love like crazy. To me a car just simply has to have power in it. Now that does not mean that we have to race it like idiots on the road so that we can endanger innocent people's lives... I just believe that lil' bit of extra power could save our lives (and other's too) sometimes when used accordingly. Try swerving by reflex away from a car almost colliding into you... what if you had no power? And let's face it, which car lover doesn't love to have a smooth running powerful car? Not everybody has a V6 or a V8 'tho. Not everybody could afford the gas it drinks for one simple mile, even with the great performance it gives. For those that have 4 cyl cars like me, even the DOHC with the power "choking" catalytic converters, different computer chips, smog control used here in America... any amount of power increase is welcome. We just have to make the best of what we do have. Tried using standard gas, midrange gas to premium gas. Tried normal oil and synthetic oil, etc. One thing is for sure... YOU GET WHAT YOU PAY FOR. PREMIUM DOES MAKE ANY ENGINE RUN SMOOTHER. Technical reasons may vary because of different points of logical viewpoints and are mostly correct in their own aspects. I agree with you too on something else. Life is too short but we will never be able to take all the money in the world we might have into the grave with us. So while alive... ENJOY! :shades:
  • shiposhipo Member Posts: 9,148
    Sorry to rain on your parade, however, Premium fuel not only does not provide extra power for engines not designed for it, it actual can lead to reduced power. Like it or not, that is the truth of the matter. The fact is that Premium fuel has a flame front that develops slower than lower octane fuels, and as such, the peak pressure point in the combustion cycle will occur too late to be of the greatest mechanical advantage. On many engines designed for Regular fuel but fueled with Premium, a significant portion of the fuel will still be burning when the exhaust port opens up, resulting in the burning fuel being pushed out into the exhaust manifold where it yields zero power. Simply a waste of money and fuel.

    Believe it or not, the designers of modern automobile engines understand the combustion process quite well, and they are very adept at developing engines that operate properly on certain grades of fuel. If your car has a fuel recommendation of Regular, then Regular is what you should be using. Period, full stop, then end. By using fuel with a higher octane rating in said car, you will be reducing your fuel economy, reducing your power and reducing your wallet in similar proportions.

    Best Regards,
    Shipo
  • kvngwynthkvngwynth Member Posts: 2
    Hmmm... :shades: Dear Shipo... Not wanting to rain on your parade either... but...

    HOW COME THEN ALL MY CARS THAT HAD POWER PROBLEMS WHEN I BOUGHT THEM USED WITH A TANK FULL OF STANDARD GAS LOST MORE THAN 75% OF THEIR POWER PROBLEMS WHEN I CHANGED THE GAS TO PREMIUM? ;) And they lost all their "knocking" problems if any. So it seems that "they", the cars do love premium better? They simply run smoother... By the way, just my two cents, if a used car already pings constantly either don't buy it or be prepared to do real doctoring on the car.
    :blush:
    1974 Renault 12 TL
    1982 Toyota Celica XT Coupe with the 22R engine
    1989 Suzuki Corsica
    1991 BMW 5 series
    1989 Nissan Sentra Coupe, "special" engine
    1995 Saturn SC2
    :)
    Logically all your arguements do make sense technically 'tho. But IMHO I think you have just forgotten that older cars need better gas... The newer the car, the better the condition all the components are still in so the lesser octane boost it needs to run as well as an older car using higher octane. Hence thus... It is just like choosing between butter and margarine. True margarine is lower in fat, etc. but true butter does make a lot of things simply taste better when cooked or baked with it compared when cooked or baked with margarine... Ironically when you have to do with a lesser, older car, the best you can do is to make the best out of the car, thereby making the best out of the whole situation for yourself. Like who wouldn't love the 4 dollars loaf of wheat bread... a lil margarine on it already tastes fine. But when you gotta do with the 1 dollar loafs of bread... a lil butter instead of the margarine helps a lot again. Now the difference between a 4 dollars loaf of bread and a 1 dollar loaf of bread is small, but try comparing a 25,000 dollars car with the 3,000 dollars car... :sick:

    Still, I know you probably mean well with your advise to all the others on here, so be safe, be happy okay?

    Sincerely,
    Gwyneth
  • shiposhipo Member Posts: 9,148
    "HOW COME THEN ALL MY CARS THAT HAD POWER PROBLEMS WHEN I BOUGHT THEM USED WITH A TANK FULL OF STANDARD GAS LOST MORE THAN 75% OF THEIR POWER PROBLEMS WHEN I CHANGED THE GAS TO PREMIUM?"

    Your anecdotal evidence not withstanding, I stand by my statements. The fact is that if any of the cars that you listed (other then the BMW 5-Series, which regardless of the engine it was equipped with, required Premium fuel) needed Premium fuel contrary to the Owner's manual to run smoothly, then there was something else wrong with the car. There can be many reasons why an older engine "seems" to require Premium, not the least of which is because the owner "thought" they were doing their engine a favor by using Premium fuel in the first place. All that will accomplish is to cause combustion chamber deposits to build up to the point where the car won't run well without it. It's sort of like a self fulfilling prophecy. Another reason older engines might seem to need premium is if the ignition timing is off a few degrees, which can be caused by worn timing chains or belts and/or bad or non existent service.

    The fact remains that if an engine was designed to run on a specific fuel and doesn't, then there are problems that need to be addressed. Using Premium fuel is essentially a "Band-Aid" and will only delay (but not eliminate) the point where said problems will need to be addressed. Sooner or later repairs will be necessary and when that point is finally reached, the cost of remediation is likely to be much higher than if the owner had just bitten the bullet in the first place and gotten the engine fixed when the problem first became evident. Now, if I had an old beater that I was planning to junk in the very near future, and it pinged heavily without Premium fuel, then I too might well be inclined to nurse it along with Premium fuel just long enough to get it to its appointment with the bone yard.

    By the way, what is a "1989 Nissan Sentra Coupe, "special" engine"? I can find no reference to it anywhere on the internet. Could said "special engine" been a custom modified mill? If so, then it comes as no surprise that it would require a higher octane fuel than was called for in the manual.

    Best Regards,
    Shipo
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    Probably the reason you think you're getting more power from premium fuel is because you, like most of us, sometimes confuse "correlation" with "cause and effect"; in other words, we don't feel good so we take some vitamins and we feel better, and therefore conclude that vitamins made you feel better.

    But actually there could have been many explanations for the "change", from purely perceptual to other environmental or physical factors.

    As this relates to cars, for instance, your car will always run better on a rainy day or a colder day; also, if you are adding something for "power" you will unconsciously press harder on the gas. You may also change brands of gas while searching for the best price for your premium fuel. So there are four new causes and effect that have nothing to do with octane rating directly.

    If your engine isn't designed to use premium fuel it won't do it a bit of good. Automotive physics doesn't seem to care about our opinions, it just does what it does.

    However, having said all this, if one of your cars had a pinging problem, then adding premium certainly would help it, as the premium fuel burns more evenly, thereby alleviating the reason for pinging (the ragged flame front).

    But if your car wasn't pinging, then your knock sensor will set your timing for the type of fuel it was designed for. If the engineers built your car to run on 87 and didn't allow for timing advance, then premium fuel won't give you any difference in performance. But if say your engine were built to tolerate just a touch of knock at 87 octane, it may very well allow a timing bump when you put in 91 octane, and you'll notice an improvement.
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,708
    Does anyone have data about how much an engine in good operating condition that is factory capable of using 87-octane will adapt the spark earlier and take advantage of 89 or 92 octane? A mechanic swears that he gets better mileage from premium and that compensates for the extra cost (low percentage these days, 5%) and with the "better running" it's worth using the premium.

    The Accord discussion has people who say that the factory states the V6 with variable valve timing will give increased horsepower on premium fuel.

    I don't want to start a battle here, but I'd also read and heard another mechanic state that the higher deposites are a problem. The first mechanic probably has mostly up-to-date, well-maintained motors, although some vehicles have higher mileage on them. I also wonder if his driving style is heavy to the metal and that helps keep the combustion chambers cleaned out...

    Myself my Buick 3800s have run well on regular and I occasionally mix in a fillup of plus and don't really notice any difference. I use brand name fuels only. I add Techron about every 20K and do note a difference when that's in the tank.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • russshprussshp Member Posts: 7
    I have just found the wonderful forum, and I have gone back and read to '03. About 8 months ago and 8000 miles ago I added a fuel additive that was invented in '87 by a chemist in my town. It was given to me as a gift and the inventor said that my car would never ever be the same again. I tried it and the results were unbelievable! RIGHT AWAY, 20% better fuel savings and the car runs and sounds better. I know if I were reading this I would be rolling my eyes too! I was so convinced about the additive I have since talked 12 people in my circle of friends to try it. All are floored at the difference. The oil almost stays an "ale" color and doesn't get dark. My uncle tried it in his tractor trailor and is getting 14% better and putting on massive mileage. If anyone is interested reply and I will steer you to the guys phone number.
  • russshprussshp Member Posts: 7
    The mixture goes in your crank case not in your tank. The performance didn't seem to go back to it's old ways after i dropped the old oil, the engine is different. The guy is in talks with huge oil companys for doing testing so dont be so sure that you woin't be seeing it in your local wal-mart very soon.
  • shiposhipo Member Posts: 9,148
    I gotta tell you, I'm rolling my eyes.

    I'm continually amazed that folks think that by adding an oil additive to their car they can achieve a significant improvement in fuel economy. The fact remains that once an engine has been started and is up to normal operating temperatures, the engine runs with very near zero internal friction. If it didn't, it wouldn't last more than a few trips to the grocery store, much less the couple of hundred thousand miles most engines are capable of.

    Best Regards,
    Shipo
  • russshprussshp Member Posts: 7
    I know I know...I am the biggest skeptic, but tell me this..my friend had his '96 Dodge diesel pick-up put on a dyno machine before a treatment just so he could prove me wrong. He did a regular oil change and added the stuff to his crank case, drove for a week ( only putting on about 200 miles) and then had the truck put on the exact same dynorun by the same tech. In the low range say about 38-39 mph, hp went from 120.8 and 360 fp/torque, after the week of driving at the exact same speeds the hp went to 179.8 and 502 fp/torque. He made me copys and I would be more than willing to fax you a copy. The company who owned the dyno were so shocked they had it serviced and tested a control truck (the owners). Everything came up true. I'm not trying to say this is the "holy grail", I'm just saying that so far EVERYONE (12 for 12) is saving money and getting a far better motor.
  • shiposhipo Member Posts: 9,148
    Call me a skeptic as well. As far as I know, there are no where near the kind of internal engine losses that you're talking about. Since you cannot get something for nothing, there has to be considerable friction related losses in a typical engine, for an oil additive to achieve what you are claiming. Physics is physics, and so far at least, what you've claimed don't add up.

    Sorry, until I see some hard science, I ain't interested.

    Best Regards,
    Shipo
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    I don't believe a word of it either. But the skeptic is always willing to be convinced.

    You can set a dyno to give you any result you wish. I can make your Honda Civic put out 800 HP if you wish...on paper I mean.

    So what's the name of this miracle product? Maybe we can find some scientific results on it rather than this anecdotal information?
  • russshprussshp Member Posts: 7
    send me an address mr host...try it for yourself. as for hard info, it is going to Lubrizol ( worlds #1 oil additive company ) for testing next month. the company invented the standard for mileage testing. i'll get him to send you a sample, and you can see for yourself
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    Thank you sincerely for your offer but I have an engine worth $12,000 and I'm not putting any strange stuff in it without credible test results. If I can't even get the product's name, well that isn't inspiring my confidence at the moment.
  • russshprussshp Member Posts: 7
    ok, ok....why am i being attacked...its not my invention! i dont sell it, make it package it...nothing. i put it in my car and it worked. thought i'd pass it on, but i guess we can just forget it was brought up.
  • shiposhipo Member Posts: 9,148
    It's not that you personally are being attacked per-se, it's just that, in the words of that fine, loyal and trustworthy valet Jeeves, "There are just too many imponderables, Sir."

    Like it or not, simple physics suggest that this miracle oil treatment that you seem to be so fond of simply cannot do what you are claiming that it can do. Trust me, I'd love to be proven wrong, but so far at least, when my nose smells "Essence of Snake", it has yet to be proven wrong.

    Best Regards,
    Shipo
  • russshprussshp Member Posts: 7
    find a friend with a an older clunker and i will see. i love the snake oil term....an oldie but a goodie. anyone who reads this, i will get some of the stuff from the guy, and send it to you. of course then, when you do see results will you be willing to eat your works. as far as name and hard info? if you read carefully, and did a google search, you would have seen that its going for OEM auto testing next month, so it has no name. someone with an older clunker step up, try it so i can be cleared.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    Well look you have to admit that any cautious person would be suspicious of a product that is presently named Brand X. Also, a claim of 20% increase in fuel mileage would constitute nothing less than the technological discovery of the century, an economical miracle, an immediate solution to the world's energy crisis and a patent worth untold billions of dollars.

    Don't take it personally. Think of this quote from Carl Sagan:

    "Extraordinary claims require extraordinary evidence".
  • stanbam3stanbam3 Member Posts: 6
    Yep, another tickled newbie that likes the brain trust here...
    Russ,
    Uh, whats his # ? How do I get 2 free samples for my vehicles?
    I looked at his web site...ok.
    I use ETHOS (dieselsmoke.com) in my 92 Civic VX and 95 Odyssey with excellent results. 0.00 carbon monoxide out of both and the emissions on a whole are super even with this horrible stuff called gasoline. RFG fuels wreak havok on older cars. However, this gent may have something and be poised for collaboration with oil companies or this may be a fair-tale. I'm open to anything that keeps my money out of oil companies hands. So, spill it...
    Thanks for allowing me to this interesting forum!

    StanBam
  • stanbam3stanbam3 Member Posts: 6
    I'm interested and my 2 hondas , both w/ 155,000 run like Swiss watches.
    I'll try some for each car if possible.
    How do we do this?

    StanBam
  • stanbam3stanbam3 Member Posts: 6
    I would like to put this in my Hondas...
    How do we do this or are you off the radar now?

    Stan
  • stanbam3stanbam3 Member Posts: 6
    So email me on this wonder product.

    Thanks

    Stan
  • jmacksan74jmacksan74 Member Posts: 2
    gas is like one of the cheapest things you put into your car, you might as well get the best, what, you save less than 2 bucks a tank buying the cheap stuff? I do not understanding paying 25000 dollars plus for an automobile and then worrying about 2 extra bucks at the pump. Put the gas in that is recommended by the manufacturer!
  • stanbam3stanbam3 Member Posts: 6
    Older cars like my 92 Civic VX are real picky with fuel. It has been maintained by my best friend who is a 25 year Honda master mechanic. It's the fuel... quality from pump to pump and variances from each production batch from refineries. It is just above dishwater. However, I still get a light valve rattle at 2100 to 2300 rpm and just ease back ever so slighlty on the accelerator and it's gone. It is the second Honda vehicle to ever come out with a VTEC engine, NSX being the first.
    The VX used to give me 60+ mpg before RFG/ oxygenated fuels.
    If I go to an area 50-70 miles away where no smog fuel is used I get almost 50 mpg and my 95 Odyssey, (155,000 OBD1) gets about 28-30 mpg. I have used Mobil 1 since 1985 exclusively bar my last change when I put in the newer QS Full synthetic 10W30 in the Civic (140,000) and 5W30 in the Odyssey. Both run great.
    I find that keeping the throttle body and butterfly clean give a sweet idle as deposits settle on the set screw. I use K+N on both cars too. Both run perfect on 87 and the Odyssey got 32 mpg on 86 octane (NON SMOG).
    Honda techs recommend 87. 89 tops and do not advocate premium as shipo very adeptly explained why...Brilliant, man.
    The 92 Civic VX has a 5 wire O2 sensor that sits directly in the junction where all 4 exhaust pipes meet then directly enter the cat. con. so unburnt fuel from premium sends false readings to the PGMFI causing it to dump more fuel. Now some Hondas have 3X 02 sensors before, inside and after the cat. con.in the exhaust route.
    Smog fuel smells bad. Non smog is like old school aromatic...
    Peace

    Stan
  • russshprussshp Member Posts: 7
    sorry i was gone for the weekend and didnt turn on a comp...let me set up a new email address (so i dont get flooded with spam to my reg. mail) and i'll send to samples...keep yuour eyes peeled for my mail...cool?
  • delmar1delmar1 Member Posts: 744
    I have a 2005 Acura TL, which calls for premium. It gets great mileage for a 270hp car...getting 25 mixed with 34mpg on the highways (great when compared to a Infiniti G35 which gets 16mpg mixed and lucky to get 25mpg on the highway).

    When I have a mixture of 50% 91 octane premium with 50% 87 octane regular, I get about 27mpg mixed with similar driving conditions.

    ????Could someone help me understand why the increase in the mileage with a mixed tank?
  • gedasbgedasb Member Posts: 1
    What type of fuel to be used is not a matter of discussion, but matter of physics.
    I think few people here already gave very good scientific explanations regarding fuel types.
    The bottom line is this: If your car is made to use premium fuel then using regular (lower octane gas) can damage the engine.
    If your car is made to use regular fuel, using premium fuel will not enhance the performance nor will it give better mileage.
  • badgerfanbadgerfan Member Posts: 1,565
    Your first bottom line statement requires a bit more explanation, as there are cars on the market now that recommend premium fuel for improved performance(ie available power) for which the manfuacturer also lists regular fuel as acceptable. These cars rely on the engines knock sensing system to "detune" the engine slightly (retard the spark timing) when under high load and the engine begins to knock with regular grade fuel. The detuning that occurs will only be implemented under high load conditions and the result is in reduced power under only these conditions, but does not damage the engine. Under light load conditions, the same engine will operate fine with low octane fuel and will not be forced to retard the spark timing as the knock condition will not occur under light load for these engines even with regular grade fuel.

    The real bottom line is: Read your owners manual. If the manual says minimum 87 octane (low altitude states where most of us live), you are OK running it on that all the time. If it specifies a minimum octane above that number then you should use the higher octane. If it specifies a minimum number but with the provision that you will obtain higher performance with premium, you are still OK using the lower octane fuel and sacrificing a bit of power under high load situations.
  • shiposhipo Member Posts: 9,148
    "Under light load conditions, the same engine will operate fine with low octane fuel and will not be forced to retard the spark timing as the knock condition will not occur under light load for these engines even with regular grade fuel."

    Well, not exactly. You see, even under light load, a car that was designed to run on premium gasoline will still advance the spark as far as it can to improve fuel economy. So, if you take this car and run it on regular gasoline, its mileage will suffer compared to what it can achieve when run with higher grades of fuel.

    Best Regards,
    Shipo
  • badgerfanbadgerfan Member Posts: 1,565
    There could be truth to your statement.

    Being too cheap to buy a car that can take advantage of premium fuel, this is an issue I will never have to deal with!

    I have all the performance I require with my 200HP regular fuel 3.0 DOHC V-6 Taurus, which manages to always do just fine on the cheapest regular grade gas I can find, which isn't all that cheap anymore. Around here, it seems almost all the gas stations, name brand or not are within a penny or two per gallon of each other. It is only when we get one of those frequent price spikes that they vary from each other, and then they usually all level off to the same price within 24 hours.

    The Taurus gets about 21-23 MPG in my 22 mile round trip daily commute and 28-31 MPG on occasional longer highway trips.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    If the engine doesn't ping audibly, there's little chance of any engine damage from lower octane fuel. No ping no problem other than decreased performance and perhaps decreased fuel economy.

    Even a light ping, very quick and temporary, is probably fine. It's that heavy, sustained pinging under load that will destroy an engine, often in dramatic fashion (can you say hole in top of piston?)
  • alittlepeevedalittlepeeved Member Posts: 2
    Okay, this is probably deemed a "flame", but whatever. I just read an article on AOL auto written by Edmunds.com editors, and I must say it's pretty pitiful that a 23 year old with no mechanic certification is getting ready to make you look like a jack [non-permissible content removed]. I did see another post referring to the loss in fuel mileage from using cheaper gas.. and I agree wholeheartedly. Unfortunately, it appears someone's head is deep in a dark place, and they don't know what the hell is going on. I will quote the most shocking thing I read in the article.

    "Does a gas expert like Beard have a preference when buying gas? 'I just watch the light on the dash. After it has been on for a day I get nervous and go to the closest station available.'"

    Why don't you have real mechanics for editors? Anyone that has seen the inside of a gas tank in the past 5 years knows that most electronic fuel pumps are located at the top of the gas tank, with hoses that run down to the bottom. What the average person isn't aware of, but most experienced mechanics should know, is that the electronic fuel pump is cooled by the gasoline in the tank. When not at all submerged in gasoline to cool it, the electronic fuel pump runs a decent risk of overheating, and therefore, failing. Keep driving around with no gas in your tank, and you will find out first hand. It is a good idea to keep at least half a tank of gas in your car at all times, not JUST for this reason, but also because the dregs settle to the bottom, and when the fuel pump is suckin the last bits of gas it has the most chance of suckin up the dregs too. That's not as big of a deal as the fuel pump needing to be immersed, though. I just can't believe this retard is in a position to give people car advice when he doesn't know how one works in the first place himself. Get a real mechanic to do it, not some dumbarse that owns a car. Please.

    Wholeheartedly, and with all due respect,

    SKW Jr.
  • alittlepeevedalittlepeeved Member Posts: 2
    I just talked to my mechanic friend, and I guess I should correct myself before I get flamed. The fuel pumps are at the bottom of the tank, I was wrong about their location, but that doesn't change the importance of keeping them immersed in gas so they have their proper designed cooling.

    Something else he reminded me of, that I didn't even think about, was the fact that the sensors that adjust for low octane are working harder to adjust than if you bought midgrade or premium. So that's another think that might break sooner because you are buying cheap gas.

    I guess this guy makes a lot of money for being an Edmunds.com editor, so he can afford to trash his cars and buy new ones every 2 years. So if you go buy a used car, and wonder why everything is going haywire and breaking with it, it was probably owned by an Edmunds.com editor.

    Anyway, I for one am going to continue putting mid grade in my 96 firebird 3.8L V6, and am not going to let it drop below a quarter of a tank. Because I WORK for my money, and I can't afford to go ragging my car out and replacing it every two years. Ya'll need to check what time it is, that's all I gotta say. Take care.

    SKW Jr.
  • sailormonsailormon Member Posts: 48
    I love not being an expert on mechanics, but like anything that helps avoid buying fuel. Just for the record I make one to two trips fl. and back to mi. on a power stroke getting 17 + or - a little mpg. Fell for the claim of a popular oil many friends use and changed to that. Guess what, my last trip down and back netted me an average of 21 mpg. This is a close ave with some fuel doing better and other stations doing worse. Seems lubricants do make a diff. We also have an old car available to try out an additive on which would be interesting. Being an artist and biologist allows me lattitude to be creative.
  • 150mphclub150mphclub Member Posts: 316
    As I was perusing the issue of "Road & Track" featuring the Porsche Cayman on the cover, I came across the question of "regular v. premium" posed to the R/T technical expert. Boiling his response down to fit in a nutshell, he said that today's advanced anti-knock sensors would protect the engine. However, one might experience a slight decrease in fuel mileage and/or power. In essence, he agrees with you.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    I think his opinion is a pretty fair assessment of what most owners would experience if they switched to a lower fuel grade, yes.

    LUBRICANTS: There's good scientific evidence that some increase in fuel mileage is possible with say synthetic oils in the engine and transmission, but the results don't indicate anything as substantial as 20% (or I should say I never yet read anything that proved that). More like 3%-5%. So maybe you'd go from 17 mpg to 18 mpg. You'd probaby want to do a month's worth of testing and average it all out, city/hwy, to be sure of what gain you might get from switching to synthetic lubricants. After all they are expensive and there's some labor involved, so you want to be sure it's all worth it to you. I'd imagine some types of vehicle and some types of driving conditions would respond better than others.
  • mbutler1mbutler1 Member Posts: 22
    JUST WANNA KNOW IF YOU ARE ANYONE OUT THERE CAN LET US KNOW THAT WE KNOW; THAT WE KNOW; THAT WE'RE GETTIN EXACTLY WHAT WE"RE PAYING FOR IN PETRO[GAS]. "THOSE REPORTS REALLY OPEN ME UP." AS WELL WELL AS MY EYES!!! :mad: :mad: :mad:
  • 9phil99phil9 Member Posts: 1
    Actually your information assumes that the fuel used during all testing was low octane to begin with, but in fact the fuel used for testing was indeed high octane. 93+
    This is the fuel that they rated the engine with while the engine was being tested for maximum horse power ratings.

    Here's why....when the compression ratio exceeds about 9.1 at the timing that is considered optimal for best horse power, low octane gas will ping.

    To counter the pinging, the ECU will then begin to retard the timing until it reaches a balance point.

    Now when the timing is retarded, the gross horse power is also reduced.

    So in order to maintain full HP at all load levels, you must use a grade of gasoline that will not ping under load at the most aggressive timing the ECU will provide for that engine.

    Thus, 93+ octane will not ping under full (or even partial) load at maximum advanced timing, therefore providing maximum HP, that would be reduced, using low (87) octane gas, and retarded timing.

    If driven conservatively, most engines with a 10.1 to 1 (or higher) compression ratio, (as in the Toyota 1ZZFE engine) will achieve a higher mileage figure using higher than the factory recommended grade.

    On the other hand, lower compression ratio engines, or systems providing less aggressive maximum timing, will waste the more expensive grade.

    Just because a manufacturer recommends a low octane rated gas does not necessarily mean that more performance can not be gained from a higher octane.

    It simply implies that the lower octane will run in the engine without causing any harm.

    And for those who rarely load their engines, and consume larger than normal quantities of gas, the lower octane will of course be less expensive to run.

    You will however lose a significant amount of power while the engine is under a moderate, to severe, load.
  • shiposhipo Member Posts: 9,148
    "Actually your information assumes that the fuel used during all testing was low octane to begin with, but in fact the fuel used for testing was indeed high octane. 93+
    This is the fuel that they rated the engine with while the engine was being tested for maximum horse power ratings."


    Your assumptions about my assumptions are incorrect. It is my understanding that both power ratings and economy ratings are performed using the recommended fuel, no more, no less.

    Here's why....when the compression ratio exceeds about 9.1 at the timing that is considered optimal for best horse power, low octane gas will ping.

    Really? I'd like to see some science to support that claim. The fact is that there are plenty of 10:1 (or greater) engines that can run optimally on Regular, it depends upon the combustion chamber design, number of spark plugs, injector type and location, and valve lift, timing and duration.

    To counter the pinging, the ECU will then begin to retard the timing until it reaches a balance point.

    Now when the timing is retarded, the gross horse power is also reduced.


    So far no argument.

    So in order to maintain full HP at all load levels, you must use a grade of gasoline that will not ping under load at the most aggressive timing the ECU will provide for that engine.

    Thus, 93+ octane will not ping under full (or even partial) load at maximum advanced timing, therefore providing maximum HP, that would be reduced, using low (87) octane gas, and retarded timing.


    Yikes! Where on earth did you come up with that little nugget? Fact, high compression/high octane, or low compression/low octane, or any combination thereof, no engine that I've ever studied uses "aggressive timing" at full power. Regardless of engine (even low compression with high octane fuel), if one was to advance the timing all of the way at WOT, not only would the engine "Ping", but the detonation would most likely hole a piston or punch a valve up into the head.

    The most "aggressive timing" available on any engine is used only at partial throttle and very light loads. When so used, said aggressive timing simply serves to aid fuel economy.

    If driven conservatively, most engines with a 10.1 to 1 (or higher) compression ratio, (as in the Toyota 1ZZFE engine) will achieve a higher mileage figure using higher than the factory recommended grade.

    First off, "If driven conservatively…", is a red herring. Driving any engine (high compression or otherwise) conservatively will not generate any benefit what-so-ever relative to higher octane fuel. If anything, it might just be the reverse of that in older cars with less capable ignition electronics.

    Secondly, it all depends upon the design of the engine once again. In the case of this specific Toyota engine, it could be that the marketing types held sway over the engineers and demanded a Regular fuel rating (unlikely but possible). As a general rule, the engineers that designed any given engine will be the ones that determine the recommended fuel. Also as a general rule, an engine will obtain both its best power and its best economy on the same type of fuel. The only exception that I can think of are blown engines with low mechanical compression of say 8:1. In that case, the effective compression ratio can vary from as little as 8:1 (quiescent blower) to as high as 16:1 (or even higher, it all depends upon the programming of the waste gate or other boost limiting devices).

    On the other hand, lower compression ratio engines, or systems providing less aggressive maximum timing, will waste the more expensive grade.

    I've been saying this for years, no surprises here.

    Just because a manufacturer recommends a low octane rated gas does not necessarily mean that more performance can not be gained from a higher octane.

    Highly unlikely in most cases, but possibly true in a very few. Why? Well, given that most manufacturers are currently engaged in two seemingly opposed "races" (being power and fuel economy) these days, being able to advertise greater fuel efficiency AND higher Horsepower and Torque numbers would certainly be an advantage. I cannot see any manufacturer (Toyota included), recommending a fuel that was other than the one that delivered the best of both worlds.

    It simply implies that the lower octane will run in the engine without causing any harm.

    I beg to differ. Every manufacturer that I've seen that produced engines that performed optimally on Premium but could tolerate Regular, says so, right in the Owner's Manual.

    And for those who rarely load their engines, and consume larger than normal quantities of gas, the lower octane will of course be less expensive to run.

    Only if the engine was designed to run optimally on that fuel, otherwise, not a chance.

    You will however lose a significant amount of power while the engine is under a moderate, to severe, load.

    Yup, no argument here.

    Best Regards,
    Shipo
  • ddarlingddarling Member Posts: 4
    Please forgive me if somewhere in this discussion it was already brought up, but 89 octane fuel was required back in the '70s as cars switched from leaded to unleaded fuel. The reason being that unleaded fuel's carbon deposits buildup more than leaded fuel does, thus around 20000 miles an engine tuned to run fine on 87 octane required 89 to stave off preignition knock. Of course back then, there were no computers to retard the timing with antiknock sensors. What's interesting is why is 87 still around? The transition of the automotive fleet from leaded to unleaded is long ago over, and probably over 90% of the cars need 89 octane for maximum fuel efficiency. And yes, nearly every car will get about 6% better gas mileage with higher octane because the computer can set the timing to a more agressive advance that produces more power and fuel economy. Try it out if you don't believe.
  • shiposhipo Member Posts: 9,148
    "Please forgive me if somewhere in this discussion it was already brought up, but 89 octane fuel was required back in the '70s as cars switched from leaded to unleaded fuel. The reason being that unleaded fuel's carbon deposits buildup more than leaded fuel does, thus around 20000 miles an engine tuned to run fine on 87 octane required 89 to stave off preignition knock."

    Three problems with that statement:
    1) Even in the bad old days of early unleaded fuel (i.e. relatively dirty burning fuel compared to recent unleaded formulations), it burned WAY cleaner than leaded fuel, and as such caused far fewer combustion chamber deposits.
    2) I used to turn a pretty fair wrench back then, and the only "unleaded" engines that I pulled apart that were carboned up were the ones that were being fed a steady diet of fuel that was of a higher octane than the manufacturer called for. Yes, engines pinged a little back then. So what? Very mild detonation is actually considered both harmless and beneficial to economy.
    3) There is no such a thing as "preignition knock". There is preignition, and there is detonation or knock. Simple truth, preignition will destroy an engine in a matter of seconds. Period, full stop, the end. Mild detonation or knock, occurs when a small pocket (or small pockets) of end gas (unburned portions of the intake charge) are heated/pressurized to the point where it/they spontaneously combust. Given that the most optimal way to run an engine is right at the point of incipient detonation, missing that fine line by a little, thus generating a little pinging simply isn't a problem. That being said, if left unchecked, detonation can get out of hand and lead to serious detonation, and that can in turn destroy an engine nearly as quickly as preignition.

    "Of course back then, there were no computers to retard the timing with antiknock sensors."

    True enough, however, starting in the 1970s, manufacturers started using knock sensors that could in turn retard the ignition timing of the engine somewhat. Even so equipped, the manufacturers still had to err on the side of component safety by de-tuning the engine so as to be able to withstand fuel quality fluctuations. Feeding such an engine higher octane fuel was simply asking for lots of carbon deposits.

    "What's interesting is why is 87 still around? The transition of the automotive fleet from leaded to unleaded is long ago over, and probably over 90% of the cars need 89 octane for maximum fuel efficiency."

    Got any science to back that up? I've studied literally hundreds of fuel and engine related scientific research projects extending back to the First World War, and I've never seen anything other than anecdotal evidence and/or wishful thinking that suggests that deviating from the manufacturers recommendations regarding fuel quality would be anything other than detrimental to said engines' performance and economy. Many engines are designed for 87 octane, and the oil companies obligingly make 87 octane fuel. That doesn't seem too mysterious to me.

    "And yes, nearly every car will get about 6% better gas mileage with higher octane because the computer can set the timing to a more aggressive advance that produces more power and fuel economy. Try it out if you don't believe."

    Ahhh, some more wishful thinking. The fact is that the higher the octane of a fuel, the greater the amount of energy required to bring the air/fuel mixture up to the temperature required for efficient combustion. Lower compression engines designed for 87 octane fuel simply don't have the ability to do that with mechanical compression. Advancing the spark might help some, however, the best power and best economy are both achieved with the fuel that the engine was designed to burn. No more, no less.

    Best Regards,
    Shipo
  • imidazol97imidazol97 Crossroads of America I70 & I75 Member Posts: 25,708
    >thus around 20000 miles an engine

    Actually that figure of benefiting from slightly higher octane was around 5000 miles and then deteriorated thereafter. And the higher octane was not required, just a possibility. What occurred was the rings seat and everything is super tight increasing the compression until wear starts to occur. The slightly higher compression efficiency could benefit with the next grade up. But it wouldn't have any long term benefit... At that time, with the then current fuels, there was a slightly noticeable tendency to pinging when that peak compression efficiency occurred.

    2014 Malibu 2LT, 2015 Cruze 2LT,

  • hoosierdadhoosierdad Member Posts: 2
    My wife has 2002 Nissan Quest with 36,000 miles on it and she is only getting about 10 mpg in the city and highway mileage is right at about 22-23. The dealer has checked fuel air mixtures and everything he says he can and reports no problem of course. This started about a year ago and has been in the shop 3-4 times for the problem.

    Any ideas on what I might look at as a possible cause of this problem?
  • another_billanother_bill Member Posts: 1
    Hi everyone.

    I have a quick question about gas quality and manufacturers. Locally, there are many gas stations, all of which are roughly the same price. One though, HESS, seems to be 7 to 15 cents cheaper then the Exxon across the street from it. I've not lived in the area long, but this is the only HESS station I've ever seen. Looking around shows that they're a fairly big company, but being that much lower in price is setting off warning bells about watered down gas and such. Anyone know about the quality of their gas? Or am I just being paranoid and throwing away money?
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    I think it's much more about the maintenance of an individual station's underground tanks than with the gas itself. I drive a lot, and I stop at ANY "decent" looking station regardless of brand to get gas and have done so for many years and never once noticed any appreciable difference in how my cars ran.

    What I do avoid is stations that look really run down, again, regardless of brand of gas.
  • Steve EliasSteve Elias Member Posts: 2,207
    my latest curiosity is about whether 92 or 93 or 94 octane does anything good for my vehicle that is optimized for 91 octane... it's probably impossible to figure that out. also i'm never sure whether to believe that fuel from a pump labelled "93 octane" is really any different from that from a pump labelled "91".
  • Steve EliasSteve Elias Member Posts: 2,207
    during the early/mid 1990s in california i ran lots of tests with our honda civics and determined that 10%-mtbe RFG1 gave better mpg than 10% ethanol RFG1. i wonder if that holds true today for whatever type of reformulated gas we have recently in the northeast (RFG2?).
    apparently 10%-mtbe gasoline is no longer available in the northeast - seems like it's all mixed with ethanol now.
  • Mr_ShiftrightMr_Shiftright Sonoma, CaliforniaMember Posts: 64,482
    This all depends on engine mapping I would guess. If your car's computer doesn't adjust engine timing to take advantage of higher than 91 octane, then indeed you are wasting your money. It was my impression that steady highway driving at constant RPM can be done with a lower octane with no disadvantage in fuel mileage or performance...that is, if you are just loafing along.
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